Expect huge amounts of derp and rage, punctuated by /tg/ extracting humor from it.
"I drop my trousers and piss on the king!"
Chaotic Stupid is yet another of the "stupid" alignments. Where Lawful Stupid characters adhere to a restrictive code of conduct beyond the point of reason, Chaotic Stupid characters are marked by their refusal to abide by any kind of code whatsoever, even when it would be reasonable to do so. Some Chaotic Stupid characters take this even further, and will actively break whatever the local laws and customs are, because "I'm chaotic, tee hee!"
Another common symptom is mistaking "chaotic" for "whatever random action pops into my head", leading to the synonym of randumb. This provides a criterion for distinguishing Chaotic Stupid from Stupid Evil -- a Stupid Evil character will take actions to cause harm, while a Chaotic Stupid character will just act out for the hell of it.
- Kender. They are "Chaotic Stupid: The Species", as they steal anything that isn't nailed down or touch anything that takes their fancy, and then have the temerity to giggle and act cute about it if things go wrong.
- The Xaositects of Planescape are a social faction dedicated to the philosophy that there is no purpose to the multiverse besides pure chaotic whim, so don't make plans and just do whatever the hell you feel like. In other words, a group for whom Chaotic Stupid is basically the explicitly recommended course. They tend to attract hate from DMs only matched by Kender.
- In a rare example of Chaotic Stupid not being a totally bad thing, the forces of Chaos in Warhammer 40,000 can exhibit some of this when their own chaotic natures cause them to fight among themselves and collapse any army that threatens the status quo. This in turn keeps the galaxy at large from being completely fucked (only mostly). With that said, sometimes GW takes this a little too far.
- Similarly, the Orks (and the Orcs and Goblins of Warhammer Fantasy Battle). The Orks in particular also have the benefit of being specifically designed as war machines, and their creators were taken out before they could enact some form of fail-safe.
- Deadpool of Marvel comics post-Liefield, but he has a good excuse in that he's completely insane from
braineverything cancer. He also subverts this many times, and occasionally manages to be actually funny, plus being almost unkillable explains how he endures any negative consequences of his actions.
- Second edition AD&D described Chaotic Neutral exactly like this. Seriously. Third edition had to specifically revoke this description, making it similar to the problem of Stupid Neutral.
- Malkavians in Vampire: The Masquerade are prone to being played like this because every member of the clan is driven irreparably and uniquely insane upon being turned into a vampire. This has led to the term "Fishmalks" originating within the community, after one particularly infamous Malkavian PC and art where one was kissing a fish.
- Olive Ruskettle, a female halfling thief from the Forgotten Realms. She stole the name of a famous bard so she could try and usurp his reputation, despite the fact she's a rogue and not a bard (and is in fact described as being "too chaotic to become one"!), feels that "any constraints are too many", dislikes and enjoys picking on anyone who holds strong but narrow beliefs and views (Lawful alignment, devout religious or moral codes, etc. with a particular dislike of paladins), and is generally described as being irrepressible, impetuous, and completely lacking in foresight.
- "Katy t3h PeNgU1N oF d00m", the supposed author of an old (first seen 2006 or so) 4chan copypasta.
- Charlie Kelly from It's Always Sunny in Philadelphia, specifically the episode "The Gang Solves the Gas Crisis". Upon being told that he was the "wild card" of the gang, he uses this role as a justification for increasingly erratic behavior, culminating in him cutting the brakes of the van they were in for no other reason than "Wild Card, bitches!"
How to be Chaotic without being Stupid
As any alignment thread on /tg/ will show you, defining the "Lawful/Chaotic" axis in a way that is totally orthogonal to "Good/Evil" is very tricky. There is also the matter that any sane character will have some internal code of conduct, so it is not possible to define Lawful as "follows some laws, any laws" and Chaotic as "follows no laws whatsoever". One potentially useful interpretation of that axis that can avoid stupidity or strawmen is to think of Lawful as emphasizing working "by-the-book" for the whole (with the nature of that book separating Lawful Good from Lawful Evil), and Chaotic as emphasizing individual freedom to achieve one's own desires (with the nature of those desires separating Chaotic Good from Chaotic Evil). A way to be Chaotic without being Stupid, therefore, is to determine the character's goals, and have them achieve those goals by whatever method they think is best. This might mean following the rules, if playing nice with the Paladin to stay out of jail is a prerequisite for that goal, but if breaking a few laws is what it takes, then so be it.
As far as that Lawful Neutral (and hopefully not stupid) guy in the party? Remember, you can find something to like about that character too. We're past the days where alignments only hung around with each other. Make a friend. Don't be uptight about chaos. It's not like you're forbidden by a code of conduct to have lawful friends, right?
Littlefinger from Song of Ice & Fire is a good example of a chaotic figure who isn't stupid (although he does eventually get done in by his web of lies). A chaotic figure who isn't stupid should be inscrutable, playing their cards close and leaving people guessing about their actual motives and who's side they're really on. This of course gets back to the problem of orthogonality mentioned before, because a person who's inscrutable is liable to be selfish and thus "evil" (like Littlefinger, who on the surface appears Lawful Evil). But this can be addressed with a bit of moral relativism, making the chaotic selfish for "their side" rather than "themselves". Ultimately the important aspect for chaotic is to be, well... Chaotic. Extreme. Willing to casually kill to fix what could be solved with words, willing to steal what could be afforded, all because it's expedient and because they can.
How to be Chaotic and Stupid without being Chaotic Stupid
Yes, it actually is possible to be Chaotic and Stupid without being Chaotic Stupid. An excellent example of how to play such a character is Elan from Order of the Stick. Elan is a brain-damaged fool with a childish innocence who constantly misunderstands situations, but he usually does not do illogical things just for the sake of being chaotic or random or for other poor excuses like typical Chaotic Stupid characters. Although he is chaotic-aligned, he doesn't have to constantly make chaotic choices to the point of stupidity, and failures or misunderstandings are rooted in his aforementioned mental condition. For the same reasons, he also completely avoids being Stupid Good as well; he does not do stupid things just because they are good. Over the course of the story, he also becomes more mature and shows that he actually can make smart decisions, although he still often misunderstands things.